Re: Measuring high impedance filters

Rod Wall

This may help,
Read the section on “Complex conjugate matching” at:
A Calculator:
You will need to 1st measure the centre frequency complex impedance for the ports for the filters. Might be easier to 1st search for the manufacturer's specifications. 
Roderick Wall.
From: n5ib@...
Sent: ‎Sunday‎, ‎October‎ ‎6‎, ‎2013 ‎7‎:‎34‎ ‎AM
To: PHSNA@...

Hi Nick,
I'd think you could use a broadband transformer. It ought to do OK over the fairly limited bandwidth of the filters.
For 50:2000 you'd need about a 1:6 turns ratio. And the reactance of the high-turns winding ought to be around 2000 ohms or better. That's around 70 uH at 5 MHz.
Ferrite cores should serve.
Or maybe a combination of techniques... 4:1 quadrafilar transformer to give 50:800 then attenuator pad to handle the remaining transformation. Wouldn't have to introduce so much loss, so maybe the level would be high enough for decent dynamic reange.
Jim, N5IB


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